Designing a bogey to have independent wheels provides numerous advantages, in particular in the following areas:
high travel speeds since the stability of such a bogey as characterized by its critical speed is very high; and
commuter vehicles with a low deck or floor since there is no longer an axle shaft to interfere with the floor which is to be located as low as possible above the rails.
Such bogies with independent wheels have already been made for load-carrying bogies.
For making a motorized bogey with independent wheels, various motorizing concepts have already been proposed, in particular concepts having one motor driving each wheel. However these solutions are not satisfactorily since they concern:
either motorizing one set of the wheels only and consequently limiting the adhesion mass of the vehicle;
or else monitoring all four wheels of the bogey in which case the motor and gear box units are not suspended and are integral with the corresponding wheels.